U.S. patent number 5,848,987 [Application Number 08/640,373] was granted by the patent office on 1998-12-15 for microtextured catheter and method for preventing catheter fluid reflux.
This patent grant is currently assigned to Medtronic, Inc.. Invention is credited to Michael D. Baudino, Maura G. Donovan, Mark T. Rise.
United States Patent |
5,848,987 |
Baudino , et al. |
December 15, 1998 |
Microtextured catheter and method for preventing catheter fluid
reflux
Abstract
A catheter having a microtextured exterior surface portion is
employed to deliver fluids such as medicaments internally to the
parenchyma of an organ or other internal living bodily tissue. The
microtextured exterior surface portion promotes cellular tissue
ingrowth into the textured surface, thereby creating an effective
fluid seal in the bore formed in the tissue and inhibiting the
body's rejection response to the catheter. The fluid seal prevents
the reflux of infused fluid from the distal end of the catheter
from the bore opening and permits controlled delivery of fluid to
affected tissue.
Inventors: |
Baudino; Michael D. (Coon
Rapids, MN), Rise; Mark T. (Monticello, MN), Donovan;
Maura G. (St. Paul, MN) |
Assignee: |
Medtronic, Inc. (Minneapolis,
MN)
|
Family
ID: |
24567987 |
Appl.
No.: |
08/640,373 |
Filed: |
April 30, 1996 |
Current U.S.
Class: |
604/500 |
Current CPC
Class: |
A61M
25/0043 (20130101); A61M 2025/006 (20130101) |
Current International
Class: |
A61M
25/00 (20060101); A61M 031/00 () |
Field of
Search: |
;604/49,50,51,93,174,175,264,265,266,272 ;623/1,11,12 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Triolo and Andrade, "Surface modification and evaluation of some
commonly used catheter materials. I. Surface properties", Journal
of Biomedical Materials Research, vol. 17, pp. 129-147(1983). .
Triolo and Andrade, "Surface modification and characterization of
some commonly used catheter materials. II. Friction
characterization" JBMR, V. 17, 149-165, (1983). .
von Recum, "New Aspects of Biocompatibility: Motion at the
Interface", Clinical Implant Materials, Advances in Biomaterials,
vol. 9, 1990. .
Campbell and von Recum, "Microtopography and Soft Tissue Response",
Journal of Investigative Surgery, vol. 2, pp. 51-74, 1989. .
Bakey, Vitek and DeLong, "Thalamotomy for Tremor", Neurosurgical
Operative Atlas, vol. 2, No. 4, pp. 299-312. .
Meyle, Wolburg and von Recum, "Surface Micromorphology and Cellular
Interactions", Journal of Biomaterials Applications, vol. 7, pp.
362-374, Apr. 1993..
|
Primary Examiner: Yasko; John D.
Assistant Examiner: Sadula; Jennifer R.
Attorney, Agent or Firm: Kinghorn; Curtis D. Patton; Harold
R.
Claims
What is claimed is:
1. A method for preventing reflux along the exterior surface of a
catheter of a fluid infused into bodily tissue through the
catheter, the method comprising the steps of:
providing a catheter in fluid communication with a source of
infusate, the catheter having a distal end, at least one fluid
discharge aperture at the distal end, and a microtextured exterior
surface portion formed of a plurality of alternating projections
and recesses, the height and depth of said projections and recesses
each being in the range of 1 to 4 microns, the microtextured
exterior surface portion being located proximal to the at least one
fluid discharge aperture;
forming a bore in living bodily tissue;
inserting the distal end of the catheter into the bore to such an
extent that the fluid discharge aperture and the microtextured
external surface portion are received in the bore closely adjacent
to the bodily tissue;
infusing fluid through the catheter to exit the catheter from the
fluid discharge aperture and into contact with the bodily tissue
forming the catheter bore;
whereby the bodily tissue immediately adjacent to the microtextured
external surface portion of the catheter exterior surface forms a
bond therewith by growing into and intertwining with the
microtextured external surface portion thereby forming a seal to
prevent the reflux of fluid exiting the catheter through the fluid
discharge opening past the seal.
2. A method according to claim 1, wherein the step of providing a
catheter includes the step of providing the microtextured external
surface portion on the catheter at the distal end thereof to extend
longitudinally inwardly from the distal end through a predetermined
distance at least equal to the depth of the bore where the distal
end is to be introduced.
3. A method according to claim 1, wherein the step of providing a
catheter includes the step of providing a hydrophilic microtextured
external surface portion.
4. A method according to claim 1, wherein the step of providing a
catheter includes the step of coating the microtextured external
surface with a hydrophilic coating.
5. A method according to claim 1, wherein the step of providing a
catheter includes the step of providing the external surface of the
catheter that is not part of the microtextured external surface
portion with a hydrophobic surface.
6. A method according to claim 5, wherein the step of providing a
catheter includes the step of providing the microtextured external
surface made of a hydrophilic polymer.
7. A method for preventing reflux along the exterior surface of a
catheter of a fluid infused into bodily tissue through the
catheter, the method comprising the steps of:
providing a catheter in fluid communication with a source of
infusate, the catheter having a distal end, at least one fluid
discharge aperture at the distal end, and a microtextured exterior
surface portion formed of a plurality of alternating projections
and recesses, the height and depth of said projections and recesses
each being in the range of 1 to 4 microns, the microtextured
exterior surface being located around the at least one fluid
discharge aperture;
forming a bore in living bodily tissue;
inserting the distal end of the catheter into the bore to such an
extent that the fluid discharge aperture and the microtextured
external surface portion are received in the bore closely adjacent
to the bodily tissue;
infusing fluid through the catheter to exit the catheter from the
fluid discharge aperture and into contact with the bodily tissue
forming the catheter bore;
whereby the bodily tissue immediately adjacent to the microtextured
external surface portion of the catheter exterior surface forms a
bond therewith by growing into and intertwining with the
microtextured external surface portion thereby forming a seal to
prevent the reflux of fluid exiting the catheter through the fluid
discharge opening past the seal.
8. A method according to claim 7, wherein the step of providing a
catheter includes the step of providing the microtextured external
surface portion on the catheter at the distal end thereof to extend
longitudinally inwardly from the distal end through a predetermined
distance at least equal to the depth of the bore where the distal
end is to be introduced.
9. A method according to claim 7, wherein the step of providing a
catheter includes the step of providing a hydrophilic microtextured
external surface portion.
10. A method according to claim 7, wherein the step of providing a
catheter includes the step of coating the microtextured external
surface with a hydrophilic coating.
11. A method according to claim 7, wherein the step of providing a
catheter includes the step of providing the external surface of the
catheter that is not part of the microtextured external surface
portion with a hydrophobic surface.
12. A method according to claim 11, wherein the step of providing a
catheter includes the step of providing the microtextured external
surface made of a hydrophilic polymer.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to catheters for the conduction of fluids to
and from internal bodily organs, and more particularly, to a
catheter having a surface to be surrounded by living tissue, at
least a portion of the surface being microtextured to promote
adhesion to and ingrowth of the surrounding tissue. The invention
also relates to a method of preventing reflux of fluid supplied to
bodily tissue by way of a catheter.
2. Description of the Related Art
Catheters have long found innumerable applications in a wide
variety of medical procedures, including both therapeutic and
diagnostic procedures. Catheters are eminently useful, for example,
as passageways for delivery of fluids to the patient and removal of
fluids from the patient. They are thus routinely employed to
conduct fluid which contains medicaments from a source thereof
directly to the tissue of an internal organ. Such catheters may be
placed in the parenchyma of an organ such as the brain or pancreas
for direct delivery of medicaments to the parenchyma, usually by
way of a bore formed in the tissue of the parenchyma by incision,
perforation or puncture.
The body acts spontaneously to reject or encapsulate a foreign body
which has been introduced into the body or a specific bodily organ.
Such phenomena in connection with implants are described with
particularity in U.S. Pat. No. 5,219,361, issued Jun. 15, 1993 to
A. F. von Recum et al. In some cases, encapsulation will impede or
halt infusion. In others, the delivery fluid will reflux from the
tissue through a space opened between the exterior of the catheter
and the tissue of the bore in which the catheter is received.
Either of these results will greatly diminish the effect of direct
infusion of medicaments on affected body tissue. The body's own
natural defense systems thus tend to frustrate the procedure.
SUMMARY OF THE INVENTION
The microtextured catheter of the invention and its method of use
according to the invention overcome some of the problems of the
prior art by attracting and enhancing tissue growth onto a portion
of the exterior surface of the catheter, thereby preventing or
minimizing the natural responses of the tissue to a foreign body
and preventing reflux of the medicament from the bore formed in the
tissue in which the catheter is received.
More particularly, a catheter for infusing fluid into a body is
provided which comprises a proximal end adapted to be placed in
fluid communication with a source of infusate, an opposite distal
end to be introduced in a bore formed in living bodily tissue, and
at least one fluid discharge aperture. In accordance with the
invention, a microtextured external surface portion is formed on
the catheter by a plurality of projections and recesses, the
relative height and depth of the projections and recesses each
being in the range of 1 to 4 microns.
As will be explained with greater particularity hereinbelow, this
construction permits the relative direction and containment of
infusate supplied to the bore through the catheter to be controlled
by the relative location and orientation of the microtextured
external surface portion and the fluid discharge aperture and by
the ingrowth of bodily tissue into the microtextured external
surface portion.
The invention also provides a method for infusing fluid into bodily
tissue which comprises the steps of providing such a catheter in
fluid communication with a source of infusate, forming a bore in
living bodily tissue, inserting the distal end of the catheter into
the bore to such an extent that the fluid discharge aperture and
the microtextured external surface portion are received in the bore
closely adjacent to the bodily tissue, and infusing fluid through
the catheter to exit from the fluid discharge aperture and into
contact with the bodily tissue forming the catheter bore.
With this method, the bodily tissue immediately adjacent to the
microtextured external surface portion of the catheter forms a bond
therewith by growing into and intertwining with the microtextured
external surface portion.
In one form of this method, the microtextured external surface
portion is disposed at a location on the catheter spaced
longitudinally inwardly from the distal end thereof and the fluid
discharge aperture to form a fluid seal between the microtextured
external surface portion and the bodily tissue surrounding the
microtextured external surface portion, whereby to form a fluid
pocket in the bore surrounding the distal end in communication with
the fluid discharge aperture.
In another form of the method, the microtextured external surface
portion is located on the catheter at the distal end thereof to
extend longitudinally inwardly from the distal end through a
predetermined distance, the distal end being inserted in the bore
to a depth which at least equals the length of the microtextured
external surface portion.
These and other features, objects and advantages of the invention
will be apparent from the ensuing description in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a partial view of a catheter according to the invention
inserted in a patient's brain, shown partially and in section, for
directly infusing medicaments into the parenchyma;
FIG. 2 is a greatly enlarged, fragmentary, diagrammatic
representation of a radial section of an exterior, microtextured
external surface portion of the catheter of FIG. 1;
FIG. 3 is a view similar to FIG. 1, but showing an alternative
embodiment of the catheter according to the invention; and
FIG. 4 is a schematic flow diagram of the method according to the
invention for preventing fluid reflux with a catheter having a
microtextured external surface portion.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings and to FIGS. 1 and 2 in particular, a
catheter 12 according to the invention comprises a proximal end
(not shown) in fluid communication with a source (also not shown)
of infusate consisting of a fluid normally containing medicaments,
a distal end 14 opposite from the proximal end and provided with a
plurality of fluid discharge apertures 16, and a catheter body 18
intermediate the proximal and distal ends. A portion 20 of the
exterior surface of the catheter body 18 is textured, while the
remaining portions are essentially smooth. More particularly, body
portion 20 is microtextured; that is, textured on a microscopic
scale, to promote cell and tissue growth into and around the
textured surface.
In use, distal end 14 and thus fluid apertures 16 are received in a
bore 15 formed in the tissue of the patient. In this instance, the
bore is provided in the patient's skull 30 and brain tissue 28 and
extends from an opening 13 thereof inwardly to a portion of the
parenchyma intended to receive fluid from catheter 12. The
microtextured external surface portion 20 of the catheter is
disposed along the length thereof at a location such that it will
be received inside the patient's body in contact with tissue
surrounding bore 15.
As represented diagrammatically in FIG. 2, microtextured external
surface portion 20 comprises a repeating pattern of peaks 24 and
valleys 26. Peaks 24 and valleys 26 are preferably square in
longitudinal or transverse section, or approximately so, whereby
the width a of each of the peaks is approximately one micron, the
height c of each peak (or the depth of each of the valleys) is
approximately one micron, and the width b of each valley is
approximately one micron as well. The preferred range for each of
these dimensions a, b, c is one to four microns.
While the preferred microtextured structure comprises alternating
projections and recesses, any contoured shape having high and low
points at intervals of approximately one to four microns is within
the scope of the invention. Experimentation has shown that this
range results in significant cellular tissue growth into and around
the microtextured portion.
Cellular tissue growth to the exterior surface of catheter 12
results in several significant advantages. First, the tissue
ingrowth opposes the body's natural reaction of encapsulating a
foreign object. Depending upon the relative location of
microtextured portion 20 along the length of catheter 12, the
tissue ingrowth may act to resist or prevent fluid reflux from
distal end 14 of catheter 12 out through bore 15 in the tissue and
its opening 13 to the exterior. As seen in FIG. 1, microtextured
external surface portion 20 of catheter 12 is bonded to the tissue
immediately adjacent to the bore. A bond such as this will block
any reflux of fluid by way of bore 15. Therefore, the bore is
effectively sealed so that virtually all the medicament flowing
through the catheter is received in the parenchyma.
The catheter is formed from a conventional urethane or silicon
material such as those commonly used for catheters. The
microtexturing formed on catheter 12 may be produced by any one of
a variety of conventional processes; for example, by a positive
photoresist process, by ion-beam texturing, by plasma etching
employing a suitable mask, or by sintering or fuising micro spheres
to the exterior surface of the catheter. Alternatively, the surface
may be molded into the product by a process described in the
aforementioned U.S. Pat. No. 5,219,361 to von Recum et al., which
is expressly incorporated herein by reference.
Upon the insertion of a catheter into a properly sized bore in
bodily tissue, the body will identify the catheter as a foreign
object and will attempt to encapsulate the catheter as a protective
reaction. This is commonly known as the foreign body response.
Encapsulation would form a relatively impenetrable surface on the
exposed tissue of bore 15 so that as fluid was delivered by the
catheter, the path of least resistance for subsequent flow would be
a passage formed by the surface tissue of bore 15 and the exterior
of the catheter, with an exit at bore opening 13. Thus permeation
of the affected tissue would be defeated.
The catheter according to the invention is intended to overcome the
body's natural tendency to encapsulate by employing microtextured
external surface portion 20 to promote tissue ingrowth into and
around the catheter. Experimentation has shown that most bodily
tissue will actively grow into and bond to such a microtextured
external surface. As seen in FIG. 1, microtextured external surface
portion 20 is formed intermediate distal end 14 of catheter 12 and
bore opening 13. Referring particularly to FIG. 2, the brain tissue
28 immediately adjacent to microtextured external surface portion
20 will grow into, interleave, and intertwine with the peaks and
valleys of microtextured external surface portion 20, whereas the
brain tissue adjacent to the smooth portions of catheter 12 will
attempt to reject or encapsulate their nontextured surfaces. This
ingrowth phenomenon causes a fluid pocket 32 to be formed, which
extends from microtextured external surface portion 20 of catheter
12 to its distal end 14. Apertures 16 are located in this fluid
pocket, and the exterior surface of catheter 12 in the pocket is
not textured whereby brain tissue will not bond to it. Similarly,
the nontextured portion of catheter body 18 between bore opening 13
and microtextured external surface portion 20 will be encapsulated
or rejected by the tissue 28. Adherence of tissue to the
microtextured portion of the catheter can be enhanced by using a
polymer with a surface modified to be hydrophilic. This hydrophilic
surface can be accomplished by either coating the surface with a
hydrophilic coating or by using a hydrophilic polymer in the
desired area. In this embodiment, the nontextured portion of the
catheter should preferably have a hydrophobic surface.
The formation of fluid pocket 32 provides significant advantages
for the retention of infused fluids by the affected tissue. In
particular, the ingrowth of cellular brain tissue into
microtextured external surface portion 20 effectively seals bore 15
so that fluid flowing delivered from apertures 16 into fluid pocket
32 cannot escape or reflux out from bore opening 13 but is instead
forced to permeate the tissue 28. Because reflux of fluid passing
through the catheter may thus be prevented, the catheter according
to the invention may be used effectively for the delivery of a wide
variety of fluids, including, but not limited to, medications,
growth factors, antisense agents, ionic solutions, antibodies,
hormones, proteins, peptides, viruses, cell suspensions,
chemotherapeutic agents, toxins, or any suitable combination
thereof. The listing of infusion agents described above is intended
to be an illustrative listing and by no means an exhaustive
identification of suitable substances to be delivered by the
catheter according to the invention.
FIG. 3 shows an alternative embodiment of a catheter according to
the invention. In this embodiment, a catheter 40 has a distal end
42, a proximal end (not shown), and a plurality of apertures 44
formed along a length of the catheter adjacent to distal end 42.
Catheter 40 passes through a bore opening 48 formed in the skull of
a patient and is received in a bore 50 formed in brain tissue 52.
In this embodiment, a microtextured portion 46 of catheter 40
extends along that entire length of the catheter that is received
in the brain tissue 52. Therefore, the brain tissue will bond to
substantially the entire length of the catheter inside bore 50. As
fluid is infused through the catheter, the fluid will be directed
to the tissue immediately adjacent to each of apertures 44.
As is apparent, the placement and extent of microtexturing on the
exterior surface of the catheter affords the surgeon significant
control and flexibility in the delivery and direction of fluid flow
from the catheter. The placement, arrangement, and orientation of
the apertures of catheter 40 may be coordinated with the extent of
and location of the microtextured portion or portions of the
exterior surface of the catheter. For example, all of the apertures
might be clustered along one side of the catheter with the
microtextured external surface portion spaced axially or radially
from the apertures, thereby to control the direction of fluid flow.
Alternatively, the apertures might be staggered over a relatively
long distance, so that a large area of tissue would be exposed
directly to the infused fluid, and this in combination with
microtextured bands spaced along the length of the catheter to
create multiple pockets.
The microtextured catheter according to the invention is ideally
suited for use with an implantable pump for the direct delivery of
fluid to the brain parenchyma. The catheter may be used with a
conventional pump, such as the SynchroMed.TM. pump commercially
available from Medtronic, Inc. of Minneapolis, Minn. This pump
delivers fluids directly to the brain parenchyma through a catheter
at flow rates of onehalf microliter per hour to three microliters
per minute.
Though the preferred embodiments are shown as directing fluids to
the brain parenchyma, the microtextured catheter according to the
invention may be utilized with virtually any human organ having
tissue which exhibits a tendency to grow into the microtextured
external surface. In the end, the microtextured catheter according
to the invention is limited only by the creativity of the user in
positioning the fluid apertures and microtextured external surface
along the length of the catheter.
While the invention has been particularly described in connection
with certain specific embodiments thereof, it is to be understood
that this is by way of illustration and not of limitation, and the
scope of the appended claims should be construed as broadly as the
prior art will permit.
* * * * *